Known transducers have a plurality of spaced, parallel transducer rods embedded in a rigid resin between a pair of spaced conducting planes disposed transversely to the rods. The resin transmits hydrostatic pressure fluctuations to the sides of the rods. For this reason, the known transducers referred to above transmit the lateral component of hydrostatic pressure fluctuations to the transducer rods. This transmission reduces the hydrostatic pressure sensitivity and, when a rigid resin is used, longitudinal expansion of the rods, as one would expect when applying a voltage to the rod ends, is clamped and impeded.
In order to attenuate lateral acoustic pressure fluctuations, the prior art has developed transducers wherein each of the longitudinal transducer rods are surrounded by a cylinder of air and disposed in a matrix of a rigid synthetic resin between a pair of spaced and parallel conducting plates. This transducer design is disclosed in the article entitled "An Optimization of 1.3.1 PZT-Polymer Composite For Deep Underwater Hydrophone Application" by C. Richard, P. Eyraud, L. Eyraud, and D. Audigier, which article was presented at the 8th International Symposium on Application of Ferroelectrics in Greenville, N.C., on Sep. 2, 1992.
Transducers which have air around the transducer rods have a number of disadvantages. Such transducers do not provide lateral support to the rods and under high pressures, such as about 3000 psi or about 200 kg/cm.sup.2, the transducer rods can dislocate sideways, rendering the transducer useless.
The transducers noted in the previous paragraph are assembled in accordance with a costly and time-consuming procedure. This assembly procedure involves preparing a solid polymer matrix of a certain thickness with a plurality of spaced cylindrical openings or wells larger in diameter that the transducer rods but corresponding to the desired spacing and location of the rods. The openings of desired size in the polymer matrix can be drilled and the conductive armature plates are cut from sheet metal. The transducer rods are positioned in a predetermined arrangement on a conducting armature plate and bonded thereto with a conducting adhesive. Then the polymer matrix is positioned on the conducting armature plate and secured to the plate with a suitable adhesive. In such a configuration, the transducer rods are disposed in the wells of the polymer matrix, with the rods and the matrix secured to the underlying conducting armature plate. Another conducting plate is then bonded to the upper level of the rods and the polymer matrix. The rods can be ground so that the rods and the polymer matrix are in the same horizontal plane.
The prior art assembly procedure is characterized by manual assembly steps which require attention to detail and exercise of individual judgement in assembling a transducer from its component parts.